Electroplating systems are commonly used to electroplate or electrochemically deposit various materials onto conductive substrates. Although many types of electroplating systems are known, a variety of problems exist in the field, as briefly enumerated below, which are currently in need of solutions.
Certain problems present in the field include an inability to make effective electrical contact with substrates while, at the same time, insulating points of electrical contact from a deposition or plating solution and maintaining a liquid seal in the deposition tank, such that there is no leakage. This may be a problem when using substrates with lower conductivity.
Moreover, problems may emanate from the resistance increase (or conductivity drop) from the point of electrical contact to the interior of the substrate, especially acute for substrates with lower conductivity. Due to this, the voltage applied at the point of electrical contact may not be the same as that seen at the interior of the substrate, leading to non-uniform deposits, with, in many cases, a greater thickness of the deposit nearer the point of electric contact than that in the interior of the substrate.
The field also includes systems that lack an adequate means of holding electrodes and substrates firmly and maintaining precise and, preferably, minimal distance between the working electrode (the substrate upon which a material of interest may be deposited), the counter electrode, and the reference electrode (if used), for effective, diffusion-limited control as well as high efficiency of the electrochemical deposition.
Issues in the field also include the maintenance of a larger area for the counter electrode as compared to the working electrode, so that the limiting electrode processes for the deposition do not occur at the counter electrode.
Additional limitations in the field include: (1) use of pumps and elaborate circulation systems which limit efficiency; (2) a lack of a hermetic seal of the deposition apparatus or plating tank such that there is minimal solvent loss, which is especially pertinent when volatile solvents are used; (3) a lack of accurate control of the applied potential at the working electrode; (4) a lack of accurate control of the total charge passed during electrochemical deposition, so that thickness, morphology, and other features of the deposit may be well controlled; and (5) a lack of amenability to automated or semi-automated electrochemical deposition.
The present invention answers these and other needs in the field and provides an electroplating device and methods of using the same.